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Does Antimatter Fall Up Or Down?
KentuckyFC writes "There are enough loopholes in the general theory of relativity to allow antimatter to fall up rather than down in a gravitational field. We've never been able to make enough of the stuff to do the experiment. But at the European particle physics laboratory at CERN, where scientists have been refining the technique for making antihydrogen, researchers are designing an experiment called AEGIS that will finally settle the matter. The idea is simple — fire a beam of antihydrogen atoms and watch which way they fall — but the details are fiendish (abstract). The answer should help solve a number of important conundrums such as why there is so little antimatter in our part of the universe and what the value of the cosmological constant is."
There's a big difference between a belief that something is most likely true, and an experiment that removes all doubt.
09F91102 no, 455FE104 nope, F190A1E8 uh-uh, 7A5F8A09 that's not it, C87294CE no. Ah! 452F6E403CDF10714E41DFAA257D313F.
Maybe from the Millitary - "A beam of Antimatter you say... no known armour would stop it you say..."
'Don't worry' said the trees when they saw the axe coming, 'The handle is one of us.'
Yes, Silly physicist PhDs doing unneccesary experiments. They could have been told the result of the experiment just by asking a random commenter on Slashdot. :)
:P
Because our understanding of physics is so consistent that it is a waste of time to test the cornercases of our theories *cough*quantum gravity*cough*dark matter*cough*dark energy*cough*
And science is all about the difference between "I think..." and "I've tested..."
If it behaves exactly as predicted, you can make another mark and continue. If not, you've found something potentially very important.
Assorted stuff I do sometimes: Lemuria.org
Antimatter *could* be different because the mathematics of GR allow it, and we haven't actually done the experiment before. I wouldn't put much faith in human intuition in these matters, considering how counter-intuitive entire GR is...
;-)
I mean, we see water falling off edges of waterfalls etc. Why should the edge of the world be any different?
Shouldn't that mean that matter-antimatter annihilation would result in no energy being emitted? If antimatter had negative mass, the net mass converted to energy would be zero.
He who lights his taper at mine, receives light without darkening me.
Until now I thought that ouside the real of mathematics (where things can be proven and no further revision is possible, save for attacking the logic of the proof), there is no such thing as "an experiment that removes all doubt"?
Ezekiel 23:20
If that were true, while it would have no practical use in the near future
Not necessarily - Merely opening that particular conceptual door would lead to a massive influx of funding and revisited anomalous past results.
Interesting thing about experimentation, even the most honest of researchers tends to throw away "bad" results (in the sense of not publishing them, not in the academically-dishonest sense of omitting them from the data). If the scientific community suddenly accepted the possibility of spooky-effect-X, you can bet that dozens or even hundreds of research groups would dredge up their past efforts to see if effect-X explains their results.
Case in point, l'Acedemie des Sciences and meteorites. Up to the turn of the 19th century, only idiots would dare claim that rocks could fall from space... Until the scientific community decided they could, at which point a huge body of past evidence appeared practically overnight supporting the existance of such falling objects.
You mean apart from all of the air in-between you and the target?
It's not science. Even doing a nice bunch of calculations and saying "Well this shows that anti-matter should do this," is not science, or at least not the important part. Science is testing beliefs by experiment. So regardless of what we think anti-matter will do, and regardless of how sure we think we are, we still need to test it. That's how science works. You come up with an idea, you test it. If the test falsifies it, you come up with a different idea and test it. If the test supports it, you come up with more tests to try and falsify it.
Through this process, we come to understand the natural world, and come to be fairly certain that our understanding is correct. Math and theoretical work is great, but actually testing those theories is what makes science what it is.
So even if we are 99.999999% certain that our calculations are solid and anti-matter does something, we still need to test it. There are plenty of things that we've been certain about that, when we tested it, turned out not to be the case.
Are you sure you have a degree in physics? Neutrinos have no charge, and thus are not affected by electromagnetic fields. The name sounds like "neutral" because of this. If they were charged they would be called something else.
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I think you are confusing molecular energy with anti-gravity.
TFA questions whether anti-matter will be attracted (mass-> <-mass), or whether it will be repulsed (mass<- ->mass) by gravity.
Hydrogen is attracted rather than repulsed by earth's gravitational pull. Whether the earth's gravity well is deep enough to keep hydrogen captive is a separate topic. Having enough energy to escape earth does not mean that it is repulsed by earth's gravity. The Space Shuttle has enough energy in its fuel tanks to reach escape velocity, and there is no doubt that is is attracted, not repulsed, by earth's gravity.
Hot air is still attracted by earth's gravity. However, its higher energy state forces it to occupy a larger volume at a given ambient pressure, which makes its density lower than the surrounding cooler air. Hot air doesn't defy gravity by rising; cool air pushes the hot air up because it is denser.
I prefer rogues to imbeciles because they sometimes take a rest.
This discussion is rather academic, however, as one of the largest problems with antimatter is creating and containing enough of it to be useful for experimentation. Creating and storing enough antimatter to be useful in a weapon is probably reserved for science fiction exclusively. H-bombs are much more efficient to produce, and equally useful as weapons---which is to say, not very.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
Hydrogen in the atmosphere does not 'fall up'. It's pushed up; it's called buoyancy. Hydrogen molecules at sea level are on average moving at less than 1/4 of Earth's surface escape velocity.
And do you honestly think that these physicists are going to be so stupid as to not do their antimatter experiments in a vacuum? That's about the only conditions where you could measure the rate of fall of individual atoms.
Don't just stand there, get that other dog!